Layer 2 of The OSI Model: Data Link Layer provides the functional and procedural means to transfer data between network entities and to detect and possibly correct errors that may occur in the physical layer. Originally, this layer was intended for point-to-point and point-to-multipoint media, characteristic of wide area media in the telephone system. Local area network architecture, which included broadcast-capable multi-access media, was developed independently of the ISO work in IEEE Project 802. IEEE work assumed sub-layering and management functions not required for WAN use. In modern practice, only error detection, not flow control using sliding window, is present in data link protocols such as Point-to-Point Protocol (PPP), and, on local area networks, the IEEE 802.2 LLC layer is not used for most protocols on the Ethernet, and on other local area networks, its flow control and acknowledgment mechanisms are rarely used. Sliding window flow control and acknowledgment is used at the transport layer by protocols such as TCP, but is still used in niches where X.25 offers performance advantages. The ITU-T G.hn standard, which provides high-speed local area networking over existing wires (power lines, phone lines, and coaxial cables), includes a complete data link layer which provides both error correction and flow control by means of a selective repeat sliding window protocol. Both WAN and LAN service arrange bits from the physical layer into logical sequences called frames. Not all physical layer bits necessarily go into frames, as some of these bits are purely intended for physical layer functions. For example, every fifth bit of the FDDI bit stream is not used by the layer.
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FAQs
The data link layer, or layer 2, is the second layer of the seven-layer OSI model of computer networking. This layer is the protocol layer that transfers data between nodes on a network segment across the physical layer.
What does the OSI layer 2 data link do? ›
Layer 2 of The OSI Model: Data Link Layer provides the functional and procedural means to transfer data between network entities and to detect and possibly correct errors that may occur in the physical layer.
What is an example of a data link layer 2? ›
Data-link protocols specify how devices detect and recover from such collisions, and may provide mechanisms to reduce or prevent them. Examples of data link protocols are Ethernet for local area networks (multi-node), the Point-to-Point Protocol (PPP), HDLC and ADCCP for point-to-point (dual-node) connections.
What is the role of the data link layer? ›
The data-link layer is responsible for transferring messages (or frame) from a given node to all other nodes in the CAN network. This layer handles bit stuffing and checksums for error handling, and after sending a message, waits for acknowledgment from the receivers.
Which is an important layer 2 data link layer function? ›
Layer 2 is known as the data link layer and is focused on traffic within a single local area network (LAN). The data link layer formats and organizes the data before sending it to the physical layer. Because it is a physical scheme, hard-coded Mandatory Access Control (MAC) addresses are typically used.
What does layer 2 do in networking? ›
Layer 2 is equivalent to the link layer (the lowest layer) in the TCP/IP network model. Layer2 is the network layer used to transfer data between adjacent network nodes in a wide area network or between nodes on the same local area network.
What are the layer 2 data link devices? ›
A layer 2 device on a computing network will transmit data to a destination according to Media Access Control (MAC) addresses, also known as Ethernet addresses. The data link layer of a multipoint network can establish a connection, segment data into frames, and manages data arrivals.
What are the two main jobs of the data link layer? ›
The two main functions of the data link layer are data link control and media access control. The first, data link control, deals with the design and procedures for communication between two adjacent nodes: node-to-node communication.
What is the data link layer in simple terms? ›
The data link layer, or layer 2, is the second layer of the seven-layer OSI model of computer networking. This layer is the protocol layer that transfers data between nodes on a network segment across the physical layer.
What are the disadvantages of data link layer? ›
When the data link layer at the destination sees the character count,it knows how many characters follow, and hence where the end of the frame is. The disadvantage is that if the count is garbled by a transmission error, the destination will lose synchronization and will be unable to locate the start of the next frame.
The Data Link layer detects these conflicts and manages how to handle them. Security: The Data Link layer plays an important role for network security. It ensures that data is protected against unauthorized access and may include mechanisms such as authentication and encryption to increase security.
Why is Layer 2 important? ›
Layer 2 scaling solutions play a pivotal role in overcoming the scalability challenges faced by blockchain networks. By offloading transaction processing to offchain networks while maintaining the security guarantees of the main chain, L2 solutions enable faster, cheaper, and more efficient transactions.
What is one function of a Layer 2? ›
A Layer 2 switch is a network device that interconnects networks at layer 2, specifically at the MAC sublayer. It functions as a bridge, building tables for the transfer of frames between networks, and emerged to address contention issues in shared media LANs.
What is the data link layer unit 2 in computer networks? ›
It allows the receiver to inform the sender if a frame is lost or damaged during transmission and coordinates the retransmission of those frames y the sender. Error control in the data link layer is ased on automatic repeat request (ARQ). Whenever an error is detected specified frames are retransmitted.
What are two services performed by the data link layer of the OSI model? ›
Specifically the data link layer performs two basic services: It accepts Layer 3 packets and encapsulates them into frames. It provides media access control and performs error detection.
What is the protocol data unit for the layer 2 of the OSI model? ›
Protocol data units of the OSI model are: The Layer 4: transport layer PDU is the segment or the datagram. The Layer 3: network layer PDU is the packet. The Layer 2: data link layer PDU is the frame.
What are the two functions of data link layer of TCP IP reference model? ›
The data-link layer identifies the network protocol type of the packet, in this instance TCP/IP. The data-link layer also provides error control and “framing.” Examples of data-link layer protocols are Ethernet IEEE 802.2 framing and Point-to-Point Protocol (PPP) framing.
